At the age of one, Harry Potter survived the killing curse, a curse which we later learn is unblockable, and vanquished Voldemort in the process. How he survived was unknown for ten years, but at the end of his first year at Hogwarts, he was told by Dumbledore that what saved him was his mother, Lily, sacrificing her life to save his.

But how much do we actually know about this protection? We are told a little explicitly in the series:

• It caused Voldemort’s curse to rebound, killing Voldemort instead of Harry
• Quirrel, possessed by Voldemort couldn’t touch Harry, and in fact touching Harry killed him
• Voldemort couldn’t possess Harry without risking his own destruction

However if we read between the lines, we find quite a number of cases where Harry was protected from harmful spells hidden throughout the series.

You might ask how Harry could be affected by (insert appropriate harmful spell here)? The answer, in my opinion, is that Harry’s protection is from spells that, when finished, leave injuries or damage that can or can’t be reversed using magic but never heal on their own.

Harry Potter and the Sorcerer’s Stone

Obviously, the place to start is the curse that didn’t kill Harry. The Avada Kedavra curse, as we learn in Goblet of Fire, is unblockable, leaves no marks on the victim, and causes no damage except killing the target. And yet, when Harry’s protection came into play, the spell was blocked, left a mark on baby Harry’s forehead, and blew up the part of the house he used it in.

However, this protection is more than just a one time event, or even just protection from one particular curse. My theory, based on the evidence produced here, is that it protects Harry from other spell damage, or in one case, damage done by a spell being lifted. It does this through active protection such as we already were informed of, and by passive protection, working in similar ways to Felix Felicis to make events conspire for Harry’s continued survival.

One example of passive protection is found at the end of the book when Harry is trying to protect the stone from Quirrel, and as Dumbledore says later “The effort nearly killed you, Harry”. It seems to me that Dumbledore arrived just in time because of the protection of Lily Potter’s sacrifice.

In fact you might even go so far as saying (and I certainly do) that the protection was responsible for Firenze, the one centaur who didn’t consider it beneath his dignity to give Harry a ride to safety on his back, being near the dead unicorn rather than wherever the rest of the herd was. It’s also responsible for the fact that when Hermione went to stop Snape, thinking he was jinxing Harry’s broom, she accidentally knocked Quirrel over.

Harry Potter and the Chamber of Secrets

While being taken from his house to be sent to Azkaban, Hagrid said that if anyone wanted answers, they should follow the spiders. Harry and Ron take that advice and find the spiders swarming into the Forbidden Forest. In the forest they come across a Ford Anglia they knew from earlier, and got snatched from behind by an Acromantula (see Fantastic Beasts) which carried them a long way, to a large colony headed by Aragog, Hagrid’s old pet. Just before they get eaten they are saved by the Ford Anglia. Now we need to understand how the car got there:

• Dobby tried to prevent Harry from getting onto the Hogwarts Express
• Ron was with Harry
• Ron suggested taking the car
• The car crashed into the Whomping Willow
• And ran off into the forest
• Only then could it happen to drive into the colony

Seems to me that at least some of these are affected by Harry’s protection to ensure that he would survive.

Later in the Chamber of Secrets, Gilderoy Lockhart tries to use a Memory Charm on Harry and Ron and, (compare with the Avada Kedavra) it rebounded on the wizard who cast it, and caused the tunnel to collapse. (It also destroyed Ron’s wand but that might be the damage to the wand)

Harry Potter and the Prisoner of Azkaban

A mere five hours after Harry’s feeble attempts at a Patronus Charm failed against “at least a hundred” dementors, he managed to arrive just in time to drive them off with a true patronus. The only previous time he managed a corporeal patronus was against Malfoy, Crabbe and Goyle, not even against a single “dementor” played by a boggart. In addition, it’s a spell which is so advanced even Hermione had trouble learning it two years later in DA meetings. It also required a chain of prerequisite events:

• Hermione took all the possible lessons
• For that purpose she was allowed a Time Turner
• Dumbledore believes Sirius Black
• He also suggests going back three hours
• Hermione, in insisting on Harry staying out of sight, neglects to keep an eye on him when he goes to see his father
• Therefore he jumps into sight when he casts the Patronus and sees himself
• And therefore knows he could do it

In addition, although not as impressive, when Harry and Hermione are attacked by the Whomping Willow, they both get hit on the head and yet neither sustained injuries that would prevent them going back in time (Harry couldn’t go back alone, Hermione couldn’t cast the Patronus).

Harry Potter and the Goblet of Fire

Malfoy is provoking Harry outside the potions dungeon, and the two attack each other. You might ask, “What’s the big deal? They attack each other all the time.” Yes they do, but there is a difference: They cast their spells at the same time and the spells meet in mid-air.

Wikipedia describes the spell Malfoy used, Densaugio, as being a combination of the Latin dens and augmentare the first meaning tooth and the second increase. However, I’ve never seen Malfoy using a spell on Harry that causes as little damage as Hermione sustained from it. My theory (assisted by my father who is a linguist) is that instead of dens we should put denso , to thicken (as to augment you would need to use the form dent for tooth), and get a high power localized version of engorgio. Malfoy and Harry were aiming for each other’s faces. Or in other words, Malfoy was trying to split Harry’s scar wide open, leaving him with a gash on his forehead.

Two spells hitting each other seems to be an uncommon event, as we almost never see it even in major pitched battles. However, it happens a second time in the same book: In the graveyard, Harry is dueling with Voldemort, they each cast their spells, and the whole Priori Incantatem sequence results. It also uses the fact that the wand cores came from the same source.

There is one more interesting point in Goblet of Fire. When Harry cracks the clue of the egg, he thinks “He wasn’t a very good swimmer; he’d never had much practice. Dudley had had lessons in their youth, but Aunt Petunia and Uncle Vernon, no doubt hoping that Harry would drown one day, hadn’t bothered to give him any.” Yet, when the effect of the gillyweed wears off, Harry manages to swim to the surface weighted down by Ron and Gabrielle, and swim to shore after (as extra emphasis?) asking Ron to help with Gabrielle because “I don’t think she can swim very well.” From which, along with other data from the chapter, I concluded that they were relatively far from the shore.

Harry Potter and the Order of the Phoenix

When Harry and Hermione led Umbridge into the forbidden forest, Hermione accidentally told the Centaurs that she was hoping they’d drive Umbridge off. The Centaurs took umbrage at Hermione’s attempt, and decided to give Harry and Hermoine the same treatment as Umbridge. Suddenly Grawp, who had been tied up stoutly by Hagrid due to his immense strength, managed to get free. Does that seem likely to have happened by chance? I think it was chance, although chance had some help from Lily Potter.

That help from Lilly showed its colors again in the battle at the Department of Mysteries. Here, after much of the battle has taken place, the prophecy breaks. This is extremely important. If Voldemort had heard the prophecy he might have realized that “He will mark him as his equal” meant that he gave Harry an equal part of his soul. This realization might have given him an opportunity to turn the tide, and kill Harry without destroying his horcrux.

Harry Potter and the Half Blood Prince

In Half Blood Prince, while Harry only gets into two major scrapes, his friends manage to get into a few of their own. It is important that his friends be protected, as he still needs them to fulfill his destiny. It is this need that allows his protection to keep his friends alive as well.

In the first Potions lesson, Harry and Ron have to borrow old textbooks. Professor Slughorn promises that whoever manages the best potion will win a bottle of Felix Felicis (Luck potion). Malfoy, who we later learn is trying to fix the vanishing cabinet to introduce Death Eaters [/u]into Hogwarts, is good at potions. Harry, himself says he got lucky by getting the Half Blood Prince’s old textbook with hand written instructions. By following these written instructions he wins the Felix Felicis. The result of his triumph keeps the luck potion out of Draco’s hands, and therefore insures that Dumbledore is alive long enough to teach him about the horcruxes.

The Prince’s Potions book was not only a help to Harry, but also helped to save Ron’s life. As a direct result of Harry using a bezoar during class, there was one available in Slughorn’s office when he needed it to save Ron from the poisoned mead.

In Voldemort’s hidden locket cave, Harry is unable to save himself from the Inferi and is moments away from being dragged into the water when a miracle happens. Dumbledore, who is “Pale as any of the surrounding Inferi”, amazingly finds the strength to cast a protective ring of fire around himself and Harry. For anyone who had any doubts about Dumbledore’s strength at the time he cast the protective ring, he is even described as “Taller than any of them”. We see other allusions to his weakened state when Harry doesn’t believe that Dumbledore can climb into the boat by himself, and when Dumbledore can hardly stand without support.

During the final battle, Harry narrowly missed getting hit by many spells. They were ricocheting around the castle, yet he isn’t hit by a single one. It also seems unlikely that the whole battle took place in under two hours, and the Felix Felicis should have run out for Ron, Hermione and Ginny. (Harry told Ron and Hermione to split the remaining nine hours with Ginny, and they had already used an hour each watching the Room of Requirement.) However they later said that the Felix worked perfectly, causing all the spells to fly harmlessly passt them.

It’s also quite fortunate, that when Harry was hiding the Potions book he marked it with a bust wearing a wig and a tiara. In Deathly Hallows we find out that the tiara is the diadem of Ravenclaw. Voldemort had turned it into a horcrux. Harry then knows where to look for it out of all the clutter of a thousand year’s worth of students hiding their contraband.

He also gets a clue about the Hallows when in the memory, Marvolo claims that his ring has the Peverel coat of arms on it. In Deathly Hallows we find that the Peverels are the original owners of the Hallows.

Harry Potter and the Deathly Hallows

My premise here in the final book of the series is that while Harry’s protection broke, it only happened once he reached the Burrow. It still kept him safe after that, but only passively, and only the bare minimum protection necessary to allow him fulfill his destiny.

In the series we find spells hitting each other in mid-air four times. The first two are in Goblet of Fire, the third and fourth in Deathly Hallows. No two such occasions have the same result, and only in one is there any explanation for the difference. During the chase leaving the Dursley’sthe spells canceled each other out, since one of the hitting Hagrid would have gotten Harry killed.

Probably the most curious of events during the chase was the strange action of Harry’s wand. I happen to disagree with Dumbledore, since golden flames don’t seem like Voldemort’s magic. I think that it was Harry’s still active protection acting for the last time to allow him to reach the wards set up by the Order of the Phoenix.

The lingering passive protection helped Harry and his friends to escape at the last second three times in Deathly Hallows. When Harry and Hermione fall into the trap at Godric’s Hollow, they manage to survive, and more importantly, they find out some information which was later useful in the Hallow quest. The second time is when instead of falling into the trap the Death Eaters set using Xenophilius Lovegood, Harry feels a sudden urge to snoop. Ignoring Hermione’s objections, he checks Luna’s room. What he finds there, shows him that Luna hadn’t been there for months, allowing them to escape from the trap with the knowledge of the Deathly Hallows quest. The third last minute escape is from Malfoy manor. Aberforth looks in on Harry and in response to Harry’s plea for help sends Dobby. Dobby manages to get them all out just before Voldemort arrives on the scene.

Ron, through the deluminator, heard Harry and Hermione mention his name. Using the extra feature, he managed to find Harry just before the locket horcrux choked Harry to death. That earned him the right to destroy the locket.

While it might sound contradictory, I also believe that his mother’s protection got them captured by the Snatchers. Harry had been calling Voldemort “You Know Who” for quite some time, but then suddenly slips up. The result of their capture was Bellatrix seeing the sword of Gryffindor and panicking. Harry was able to correctly interpret this response, and therefore find the next horcrux.

Conclusion

Of course, we should not forget that Harry sacrificed himself at the end of the book. His sacrifice protected all those for whom he was willing to die. But this brings up two questions. According to Dumbledore, what allowed Lily to protect Harry, was the fact that she wasn’t going to die otherwise. So how did his willingness to die protect them? And what does this have to do with his protection?

The answers are related. Harry, being sentenced to death, actually didn’t have the ability to protect someone. It just wouldn’t be any more affective than what James tried. However there is one difference. In this case they were willing to lay down their lives for Harry. He chose, out of love, not to accept that sacrifice. He agreed to die sooner rather than allow Voldemort to kill his friends. By doing that, he re-awakened Lily’s protection, and defined his well-being as including the well-being of his friends. Therefore his protection kept them safe from Voldemort.